code: def test_backwards_compatibility(self):
      model = tfidfmodel.TfidfModel.load(
          datapath("tfidf_model_3_2.tst")
      )
      # attrs ensured by load method
      attrs = ["pivot", "slope", "smartirs"]
      for a in attrs:
          self.assertTrue(hasattr(model, a))
      # __getitem__: assumes smartirs attr is present
      self.assertEqual(len(model[corpus]), len(corpus))
  
file_path: gensim/gensim/test/test_tfidfmodel.py
imports: import logging
  import unittest
  import numpy
  from gensim.corpora.mmcorpus import MmCorpus
  from gensim.models import tfidfmodel
  from gensim.test.utils import datapath, get_tmpfile, common_dictionary, common_corpus
  from gensim.corpora import Dictionary
label_desc: Use image node_id 9 for calling the TestTfidfModel obj's underlying member method code with example usage: obj.test_backwards_compatibility() without return types